In many instances, it is considered (or may, due to advancements in medical science, be considered in the future) to be necessary or advantageous to inject certain substances, such as medications or suspensions of organic matter such as cells, into the human body. Often, such injections require relatively high levels of precision, both in terms of the precise location (or locations) within the body at which the relevant substance is administered, and also in terms of the quantity of the substance and the rate of delivery thereof.
Canadian Patent No. 2,282,007 describes a neural transplantation delivery system. The neural transplantation delivery system includes a threaded plunger driver which cooperates with a threaded drive nut to control movement of a plunger so as to control the metered administration of a fluid, and also includes a threaded guide nut which rotates within a threaded plunger guide to effect linear movement (insertion and withdrawal) of a syringe and attached transplantation cannula. In particular, rotation of the guide nut translates to linear movement of the syringe and cannula. The nature of this arrangement requires that the threaded drive nut and guide nut be co-rotated precisely during insertion and withdrawal of the cannula to avoid relative movement of the syringe barrel and the plunger. Also disclosed is a cannula having a closed tip and diametrically opposed offset holes to effect deposition of fluid in a spiral pattern as a result of the rotation of the cannula during withdrawal from an injection site.
Canadian Patent No. 2,282,007 corresponds to U.S. Pat. No. 7,137,969, and both of these documents are hereby incorporated by reference in their entirety.
Both the threaded drive nut and the guide nut of the neural transplantation delivery system described in Canadian Patent No. 2,282,007 must be manually rotated by the surgeon. Because the threaded drive nut and guide nut of the neural transplantation delivery system described in Canadian Patent No. 2,282,007 must be co-rotated precisely during insertion and withdrawal of the cannula to avoid relative movement of the syringe barrel and the plunger, there is a risk of adverse effects, such as unintentional injection of fluid, or unintentional withdrawal of fluid, if the synchronization is not sufficiently precise. In addition, precision in the amount of fluid administered is limited by the surgeon's manual dexterity.